[Ace-users] Re: [ciao-users] Component stoping with Dance

[Gan Deng]

Hi Steve,

James, Steven wrote:
> Hi Gan,
> 
> Looking at the
> http://www.omg.org/news/meetings/workshops/RT_2006_Workshop_CD/071_Deng_
> eta.pdf
> 
> I could use Add_instance and remove_instance?

I'm sorry that the above slides are a bit outdated. Surely you can add 
and remove instances, but you must use the below operation on the 
ExecutionManager interface to do that:

     void perform_redeployment (in DeploymentPlan new_plan)
       raises (PlanError,
               InstallationFailure,
               UnknownImplId,
               ImplEntryPointNotFound,
               InvalidConnection,
               InvalidProperty,
               ::Components::RemoveFailure);

Assume you have an existing deployment plan, and you want to remove one 
instance from it, then you can create a new plan which is the almost the 
same as the existing deployment plan without the component in interest. 
DAnCE provides a utility class (DAnCE_Utils) that can facilitate this. 
For example, you can use below method in the utility class to manipulate 
your deployment plan.

DAnCE_Utils::remove_instance (::Deployment::DeploymentPlan 
&deployment_plan, const char *instance_name)

After this method, you can get a new deployment plan with the component 
in interest removed, then you can call the perform_redeployment() in the 
ExecutionMamanager to do the actual removal.

> Is ReDaC part of the OMG's D&C standard? And what version of CIAO is
> this part of I can't see it within 0.5.10? 

No, ReDaC is CIAO specific. Since OMG's D&C is motivated by the JTRS 
(joint tactical radio system), which is quite static, it does not 
provide any mechanism to do the redeployment and reconfiguration.

CIAO 0.5.10 provides the ReDaC functionality, and you can follow the 
step-by-step tutorial to work through an example.

> Furthermore, how redundant are the ReDaC and Dance demons i.e. what
> happens if a NodeManager dies for instance? Is this documented anywhere?

ReDaC does not require any additional daemons than the D&C spec-defined 
ones, instead, ReDaC provides you the functionality by extending the 
CCM-defined interfaces.

Regarding your question of NodeManager failure (which is typically 
caused by node failure), it is an orthogonal issue, since it requires 
special fault tolerant and fault recovery support. Andy, could you 
please give Steve some input about this?

Thanks,
Gan